Sapphire has an index of refraction of 1.77. The critical angle for sapphire in air with an index of refraction of 1.0 is degrees.

The  value is  

Explanation:

From the question we are told that

   The  index of refraction is  

   The  refractive index of air is  

Generally the critical angle is mathematically represented as

=>    

=>    

=>    

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

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as we probably am aware that our atmosphere or air have various levels, each level has different gasses, and each gas has another porousness. at the point when the light originates from lower porousness to higher penetrability, it alters its course. with the goal that implies that when the light originates from the moon to the earth, it alters it's course a lot more occasions. it essentially implies that the state of the light piece of the moon is changed on the earth.

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